TextMate is cool but is not free. Netbeans and Eclipse look like overkill for scripting languages. Basically I just want autoindent, syntax highlight and maybe autocomplete. Actually I just discovered Komodo, but wonder if there's something else.
Smultron could be ok, but can't figure out if and how autoindent works for Python.
I have heard good things from PC people about SciTe but it seems like there's no Mac port.
ViM, please no, I'd rather prefer using XEmacs at that point. Both editors are ok, and UNIX de-facto standards, but I used them a loooooot of years ago during my first years at University where I learned most of the key combinations, but have removed them from mind, and don't feel like I want to learn them again.
BBEdit has a free cousin named TextWrangler and does indenting and Python syntax coloring. NetBeans and Eclipse are a little bloated I agree. I generally stick with BBEdit as it's lightweight, but I'm still hoping for language aware auto-completion to make the feature list. Smultron is nice too. You may want to consider Xcode as well, but may be a bit bloated as well.